Male rats of the JCR LA-corpulent strain spontaneously develop atherosclerosis and myocardial lesions If corpulent. The corpulent rats exhibit a marked very low density hyperlipidemla and Insulin resistance. The incidence of both vascular and myocardial lesions correlates strongly with the hyperinsullnemia, but not with the hyperllpldemia. Corpulent male rats were chronically treated with nifedipine or acetylsallcytlc acid to explore the roles of smooth muscle spasm and platelet activity In Induction of the myocardial lesions. Acetylsalicylic acid treatment was associated with no significant changes In fasting glucose, Insulin, or lipld concentrations. Nifedipine caused no significant changes In glucose concentration but was associated with mildly Increased insulin levels. Treatment with nifedipine resulted In significant decreases In serum trlglycerlde concentrations. The decreases were confined to longer-chain trlacylglycerol molecular species with no change in the concentration of molecular species with 48 or 50 acyl carbon atoms. There was no effect on myocardial lesion frequency with acetylsalicylic acid treatment. In contrast, nifedipine prevented the development of old organized scarred lesions. This effect is similar to that seen with treatments that markedly reduce the Insulin resistance. These findings suggest that platelet-initiated thrombus formation Is not an Important factor In lesion formation In the JCRLA-cp rat, but that smooth muscle spasm Is probably Important.
Arteriosclerosis – Wolters Kluwer Health
Published: Jul 1, 1990